A United Launch Alliance Delta IV rocket lifts off from Space Launch Complex 37 at Cape Canaveral Air Force Station at 8:29 p.m. on 7 August 2013 to deliver a joint U.S.-Australian military communications satellite into orbit. Due to the sky brightness at dusk this is actually a composite image made from nine consecutive 25-second time exposures of the launch. The view is almost edge on to the rocket's trajectory hence the dramatic angle of the arc.

Read more about the mission from the ULA press release:

United Launch Alliance (ULA) is proud to be a part of the WGS-6 mission with the U.S. Air Force Space Command’s Space and Missile Systems Center (AFSPC/SMC). The WGS-6 mission marks the 23rd Delta IV launch and the fourth launch of the Delta IV Medium+ (5,4) launch vehicle configuration.

This WGS mission is the sixth installment of the Wideband Global SATCOM (WGS) system. The WGS satellites are an important element of a new high- capacity satellite communications system providing enhanced communications capabilities to our troops in the field for the next decade and beyond. WGS enables more robust and flexible execution of Command and Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4lSR), as well as battle management and combat support information functions. The WGS constellation augments the existing service available through the UHF Follow-on satellite by providing enhanced information broadcast capabilities.